Various types of feed mechanisms exist in the machine tool industry to automate the loading and/or unloading of workpieces into and out of a machine tool. In this regard, it is desirable with respect to both production speed and safety to automatically place workpieces into the machine tool prior to a machine operation and then to automatically remove the workpieces from the machine tool when the machining operation or operations are complete. The intervention of machine tool operators during the process slows the production time and presents additional dangers to the operator.
Many automated loading and unloading devices are too complex and expensive to justify their use in any but the most elaborate and expensive machine tools. Such loading and unloading mechanisms may include, for example, robotic devices or other programmable or otherwise electrically controlled arms, indexing devices, etc. While needs exist in the industry for these sophisticated and expensive machine tool loading and unloading mechanisms, especially in connection with many high volume machining operations, these solutions to the problems associated with manual loading and unloading operations can be too expensive.
One air operated loading and unloading device that solves many of the problems typical of manual loading and unloading operations is disclosed in U.S. Pat. No. 5,505,584 (the '584 patent), assigned to the assignee of the present invention and the disclosure of which is hereby incorporated herein by reference. Using this device, a workpiece may be unloaded and/or loaded via a concentric tubular arrangement. The tubes rotate with respect to each other to facilitate either an unloading operation or a loading and unloading operation with respect to a machine tool spindle. Although the apparatus disclosed in the '584 patent performs well, drawbacks have been experienced with respect to the need to closely fit the inner and outer concentric tubes for adequate, repeatable sealing. For these reasons, improvements related to the ability to adequately and repetitively seal the inner chamber of the concentric tube arrangement are in continuing need.
Another problem related to the machine tool industry is related to detecting when a workpiece is fully received within the machine tool spindle after actuation of a loading device, such as the device disclosed in the '584 patent. When a mechanical device, as opposed to an air operated device, is used to feed a workpiece into a machine tool, a switch or other detection system can indicate full movement of the mechanical feeder and the attached workpiece into the machine tool. When air is used, however, it becomes more difficult to integrate a detection system. In this regard, it is generally impractical to connect hardwired detectors to a rotating machine tool turret to indicate the presence of a workpiece in the spindle of the machine tool. In such a case, the wires will interfere with rotation of the turret. Also, mounting in other locations of the machine tool proximate the spindle may not be possible.
Improvements related to the machine tool industry, and more specifically related to air operated loading and unloading devices therefore continue to be necessary.